Update buildpack ruby 1.8.7 to patch level 375

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Update buildpack ruby to 1.9.2-p321

Signed-off-by: Onsi Fakhouri <onsi@pivotallabs.com>
Update buildpack ruby to 2.0.0-p353

Signed-off-by: Onsi Fakhouri <onsi@pivotallabs.com>